TWI481181B - Dc to ac power conversion apparatus and method thereof - Google Patents

Description

DC to AC power conversion device and method thereof

The present disclosure relates to the technical field of a power conversion device, and more particularly to a DC-to-AC power conversion device and method.

The traditional DC-to-AC power converter converts and regulates the DC source through a set of DC/DC converters, and then converts the DC-to-DC converter into a DC-to-AC inverter. (DC/AC inverter) generates positive and negative alternating AC power, and finally filters the high frequency signal of the AC power supply by LC filter to output.

In other words, the conventional DC-to-AC power converter needs to pass through a group of bridge switches to form a DC-to-AC inverter to generate positive and negative alternating AC power before filtering the AC power. The bridge switch is usually a plurality of switching elements, which is a great burden for the cost of the DC-to-AC power converter. Moreover, the bridge switch causes energy loss during switching and conduction, which will affect the conversion efficiency of the DC-to-AC power converter. At the same time, in order to make the bridge switch operate normally, the controller and the driving circuit need to be added, so that the complexity of the control circuit is greatly increased, so that the difficulty of circuit design is improved.

Therefore, how to solve the above-mentioned lack of the prior art to improve the conversion efficiency of the DC-to-AC power converter and reduce the complexity of the circuit design has become an important issue for those skilled in the art.

The present disclosure provides a DC-to-AC power conversion device and a method thereof, wherein a switching operation is used to control the conduction of each switching element by using a switching control strategy to control the zero-voltage of the primary side of the power conversion module and zero-current switching of the secondary side. Cut-off or high-frequency switching to reduce the switching loss of each switching element and reduce the electromagnetic interference caused by the switching action, thereby improving the conversion efficiency of the DC-to-AC power conversion device.

The present disclosure provides a DC-to-AC power conversion device including a first power conversion module, a second power conversion module, and a control module. The first power conversion module has a first transformer, a first switching element and a second switching element, and the two ends of the primary side of the first transformer are electrically connected to the DC input end and the first switching element, respectively. The two ends of the secondary side coil of a transformer are electrically connected to the second switching element and the AC output end, respectively. The second power conversion module has a second transformer, a third switching element and a fourth switching element, and the two ends of the primary side coil of the second transformer are electrically connected to the DC input end and the third switching element respectively. The two ends of the secondary side coil of the second transformer are electrically connected to the fourth switching element and the AC output end, respectively. The control module has a voltage valley detector, the voltage valley detector detects or predicts the valley voltage of the resonance voltage to generate a conduction number, and the control module generates the first, second, third and third according to the communication number. a fourth switching signal, wherein the first, second, third, and fourth switching elements are respectively controlled by the first, second, third, and fourth switching signals, so that the first power conversion module and the first The second power conversion module converts the input current of the DC input terminal into an output current of the AC output terminal.

The present disclosure also provides a DC-to-AC power conversion method, including: generating an AC reference signal and an AC crossover zero detection signal; generating an error signal according to the AC reference signal and an output current or an output voltage of the AC output; The input current of the signal and the DC input generates a cutoff signal; detecting or predicting the bottom voltage of the resonant voltage to generate a pilot number; generating the first and second according to the AC crossover zero detection signal, the cutoff signal, and the pilot number Third and fourth switching signals; and causing the first, second, third, and fourth switching signals to control the first, second, third, and third of the first power conversion module and the second power conversion module, respectively The four-switching component causes the first power conversion module and the second power conversion module to convert an input current of the DC input terminal to an output current of the AC output terminal.

The disclosure can eliminate the bridge switch of the conventional DC-to-AC inverter, thereby reducing the manufacturing cost of the DC-to-AC power conversion device, and reducing the volume of the power conversion module, so that the power conversion module and the control The circuit design of the module is much simpler.

The embodiments of the present disclosure are described in the following specific embodiments, and those skilled in the art can easily understand other advantages and functions of the disclosure by the contents disclosed in the specification, and can also be implemented by other different embodiments. Or application.

1A and 1B are circuit diagrams showing a first type of power conversion module and a control module in the DC-to-AC power conversion device of the present disclosure. As shown, the DC-to-AC power conversion device 100 operates in a grid connected mode and includes a first power conversion mode. The group 110, the second power conversion module 111, and the control module 130.

The first power conversion module 110 has a first transformer T ₁ , a first switching element S ₁ , a second switching element S _{2 ,} and a first capacitor C ₁ . The first transformer T ₁ may be an isolation transformer, and the first switching element S ₁ or the second switching element S ₂ may be a gold oxide half field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT).

The first side coil N _{1 of} the first transformer T ₁ is electrically connected to the DC input terminal DC _in and the first switching element S ₁ , respectively, and the _two ends of the second transformer N _{2 of} the first transformer T ₁ are respectively electrically connected to the second switching element S ₂ and AC output AC _out, the first capacitor C ₁ connected in parallel to the line of the secondary side coil N ₂ and the second switching element S _2.

The second power conversion module 111 has a second transformer T ₂ , a third switching element S ₃ , a fourth switching element S _{4 ,} and a second capacitor C ₂ . The second transformer T ₂ may be an isolation transformer, and the third switching element S ₃ or the fourth switching element S ₄ may be a gold oxide half field effect transistor (MOSFET) or an insulated gate bipolar transistor (IGBT).

The second transformer T ₂ of the primary side coil N ₃ on the two ends are electrically connected to the DC _in and DC input terminal of the third switching element S _3, T ₂ of the second transformer secondary winding N ₄ two ends are electrically connected to the fourth switching element S _4, and the AC output AC _out, the second capacitor C ₂ connected in parallel based on the secondary winding N ₄ and the fourth switching element S _4.

The first power conversion module 110 described above is configured to generate a positive half cycle of the output current I _out or the output voltage V _out . During the positive half cycle, the first switching signal V _g1 is high frequency switching (fast switching ON/OFF), the second switching signal V _g2 is off (OFF), and the third switching signal V _g3 is off (OFF) The fourth switching signal V _g4 is ON.

When the first switching signal V _g1 is ON, the input current I _in (the primary side current I _P1 ) of the DC input terminal DC _in flows through the first switching element S ₁ and is once by the first transformer T ₁ The magnetizing inductance of the side coil N ₁ stores the energy of the input current I _in ; and when the first switching signal V _g1 is OFF, the energy passes through the secondary side coil N _{2 of} the first transformer T ₁ and the second A body diode inside the switching element S ₂ is output to the AC output terminal AC _out .

Similarly, the second power conversion module 111 is configured to generate the negative half cycle of the output current I _out or the output voltage V _out . During the negative half cycle, the first switching signal V _g1 is OFF (OFF), the second switching signal V _g2 is ON (ON), and the third switching signal V _g3 is high frequency switching (fast switching ON/OFF) The fourth switching signal V _g4 is OFF.

When the third switching signal V _g3 is ON, the input current I _in (the primary side current I _P2 ) of the DC input terminal DC _in flows through the third switching element S ₃ and is once by the second transformer T ₂ The magnetizing inductance of the side coil N ₃ stores the energy of the input current I _in ; and when the third switching signal V _g3 is OFF, the energy passes through the secondary side coil N _{4 of} the second transformer T ₂ and the fourth A body diode inside the switching element S ₄ is output to the AC output terminal AC _out .

The control module 130 has a voltage valley detector 131, an AC waveform generator 132, a feedback network 133, a pulse width modulation (PWM) comparator 134, and a switching signal generator 135.

The voltage valley detector 131 is configured to detect or predict a valley voltage of the resonant voltage to generate a conduction signal T _ON , and electrically connect the first auxiliary coil N _{a1 of} the first transformer T ₁ and the second transformer T _{2 .} The second auxiliary coil N _a2 , and the first auxiliary coil N _a1 and the second auxiliary coil _{Na 2} are respectively disposed on the primary side of the first transformer T ₁ and the second transformer T ₂ .

When the secondary side current I _{s1 of} the first transformer T ₁ or the secondary side current I _{s2 of} the second transformer T ₂ is output to the AC output terminal AC _out and drops to zero current, the first auxiliary winding N _a1 The resonant voltage is generated by the first voltage signal V _a1 or the second voltage signal V _{a2 of} the second auxiliary winding _Na 2 , and the valley voltage of the resonant voltage is lower than the zero voltage.

Moreover, when the first voltage signal V _a1 or the second voltage signal V _a2 drops to the zero voltage, the voltage valley detector 131 detects the zero voltage to be below the zero voltage (inclusive) The conduction signal number T _ON is generated, and the first switching signal V _g1 , the second switching signal V _g2 , the third switching signal V _g3 or the fourth switching signal V _{g4 is} turned on according to the falling edge of the guiding communication number T _ON .

The AC waveform generator 132 is operated in a commercial parallel mode for generating an AC reference signal AC _ref and an AC crossover zero detection signal AC _ZCD according to the mains voltage V _grid .

The feedback network 133 is electrically connected to the AC waveform generator 132 and the AC output terminal AC _out , and generates an error signal Error according to the AC reference signal AC _ref and the output current I _{out of} the AC output terminal AC _out .

The pulse width modulation comparator 134 is electrically connected to the feedback network 133 and the DC input terminal DC _in to generate a cutoff signal T _OFF according to the error signal Error and the input current I _in , and according to the cutoff signal The rising edge of T _OFF is turned off by the first switching signal V _g1 , the second switching signal V _g2 , the third switching signal V _g3 or the fourth switching signal V _g4 .

The switching signal generator 135 is electrically connected to the AC waveform generator 132, the pulse width modulation comparator 134 and the voltage valley detector 131, and according to the AC crossover zero detection signal AC _ZCD , the cutoff The signal T _OFF and the communication signal T _ON generate the first switching signal V _g1 , the second switching signal V _g2 , the third switching signal V _g3 and the fourth switching signal V _g4 to respectively control the first switching element S _1, the second switching element S _2, S ₃ of the third switching element and the fourth switching element S _4, such that the first power conversion module 110 and the second power conversion module 111 converts the DC input terminal DC _in the input current I _in for the AC output AC _out of the output current I _out.

Further, the above-described DC-to-AC power conversion device 100 may further include a filter 120. One end of the filter 120 is electrically connected to the first power conversion module 110 and the second power conversion module 111, and the other end is electrically connected to the AC output terminal AC _out , and the filter 120 is used for filtering The high frequency signal of the secondary side current I _S1 or the secondary side current I _S2 .

2A and 2B are circuit diagrams showing a second power conversion module and a control module in the DC-to-AC power conversion device of the present disclosure. The second type is substantially the same as the first type of power conversion module and control module of the above 1A and 1B, so the details are not repeated here. The main differences are as follows: in Figures 2A and 2B The DC-to-AC power conversion device 100 is operated in a stand-alone mode, and the commercial power voltage V _{grid of} FIG. 1A is changed to the load 121. The AC waveform generator 132 also operates in an independent mode and generates an AC reference signal AC _ref and an AC cross-point detection signal AC _ZCD . The feedback network 133 generates an error signal Error according to the AC reference signal AC _ref and the output voltage V _{out of} the AC output terminal AC _out .

FIG. 3 is a schematic circuit diagram of a third power conversion module in the DC-to-AC power conversion device of the present disclosure. The third type is substantially the same as the second power conversion module of FIG. 2A above, so the details are not repeated again. The main differences are as follows: In FIG. 3, the first power conversion module 110 has parallel connections. a second switching element S ₂ of the two first diode D _1, so as to strengthen the function of the second switching element S ₂ of the internal body diode of the secondary-side current I _S1 easily flow through the second switching element S ₂ The body diode and the first diode D ₁ are output to the AC output terminal AC _out .

Similarly, the second power conversion module 111 also has a second diode D ₂ connected in parallel to the fourth switching element S ₄ , thereby strengthening the function of the body diode inside the fourth switching element S ₄ , so that the secondary side The current I _{S2 is} apt to flow through the body diode of the fourth switching element S ₄ and the second diode D _{2 to} be output to the AC output terminal AC _out .

4 is a circuit diagram showing a fourth power conversion module in the DC-to-AC power conversion device of the present disclosure. The fourth type is substantially the same as the second type of power conversion module of FIG. 2A above, so the details are not repeated again. The main differences are as follows: In FIG. 4, the DC-to-AC power conversion device 100 includes a front end. Front end DC/DC converter 140. The front-end DC-to-DC converter 140 can be a step-up, step-down or any type of converter, and one end thereof is electrically connected to the DC input terminal DC _in , and the other end is electrically connected to the first power conversion module 110 . And a second power conversion module 111.

The input current I _{in of} the DC input terminal DC _in is firstly regulated by the front-end DC-to-DC converter 140, and input to the first power conversion module 110 and the second power conversion module 111, and then converted into an AC. The output current I _{out of the} output terminal AC _out can make the use range of the input current I _in wider, and increase the power generation benefit of the first power conversion module 110 and the second power conversion module 111. Meanwhile, the front end DC to DC converter 140 also has the input current I _in eliminating the effect of the ripple can be reduced input capacitance of the filter capacitor.

FIG. 5 is a schematic circuit diagram of a third control module in the DC-to-AC power conversion device of the present disclosure. The third type is substantially the same as the first type of control module of Figure 1B above, so the similarities are not repeated. The main differences are as follows: In Figure 5, the switch with synchronous rectification function (synchronous rectifier function) The signal generator 136 is configured to synchronize the first switching signal V _g1 and the second switching signal V _{g2 to} generate a corresponding high frequency switching. When the first switching element S _{1 is} cut off as shown in FIG. 1A, and the first transformer T ₁ stored energy is passed through the secondary side coil N _{2 of} the first transformer T ₁ , the body diode inside the second switching element S ₂ or the first diode D ₁ connected in parallel (eg When the output is to the AC output terminal AC _out , the second switching signal V _g2 can synchronously turn on the second switching element S ₂ to achieve the synchronous rectification function and achieve the effect of improving efficiency.

Similarly, the switching signal generator 136 with synchronous rectification function is also used to synchronize the third switching signal V _g3 and the fourth switching signal V _{g4 to} generate a corresponding high frequency switching, as in the third switching element as shown in FIG. 1A. S _{3 is} off, and the energy stored in the second pressure transformer T ₂ is via the secondary side coil N _{4 of} the second transformer T ₂ , the body diode or phase inside the fourth switching element S ₄ When the second diode D _{2 is} connected in parallel (as shown in FIG. 3 ) and outputted to the AC output terminal AC _out , the fourth switching signal V _g4 can synchronously turn on the fourth switching element S ₄ to achieve synchronous rectification function, and Achieve the effect of improving efficiency.

FIG. 6 is a schematic diagram showing the waveforms of the secondary side current, the voltage signal of the auxiliary coil, and the conduction number in the operation principle of the voltage valley detecting function of the present disclosure.

As shown in FIG. 6 and FIGS. 1A to 1B, when the first switching element S ₁ or the third switching element S ₃ is turned off (OFF), the first transformer T ₁ or the second transformer T ₂ is stored. The energy is output to the AC output terminal AC _out via the secondary side coil N ₂ or the secondary side coil N ₄ such that the secondary side current I _{S1 of} the first transformer T _{1 or} the secondary side current of the second transformer T ₂ I _S2 decreases as the energy is output.

When the secondary side current I _S1 or the secondary side current I _{S2 is} output to the AC output terminal AC _out and drops to the zero current I ₀ , the magnetizing inductance of the first transformer T ₁ and the total combined capacitance in the circuit ( the transformer T includes a first stray _capacitance and a first switching element S ₁ of the output capacitance) resonates, so that the first switching element S ₁ of the drain electrode to the source voltage V _DS1 and the first auxiliary winding N _a1 The first voltage signal V _a1 generates a resonance voltage V _r ; or the magnetizing inductance of the second transformer T2 and the total capacitance in the circuit (including the stray capacitance of the second transformer T ₂ and the output of the third switching element S ₃ ) capacitance) resonates, so that the drain of the third switching element S ₃ to the extreme resonance voltage V _r V _DS3 source voltage and the second voltage signal V _a2 of the second auxiliary winding N _a2.

When the first voltage signal V _a1 or the second voltage signal V _a2 passes through the zero voltage V ₀ , the generation of the resonance voltage V _r can be known, and the bottom of each resonance voltage V _r can be measured through an appropriate delay. Voltage V _b . At the same time, when the first voltage signal V _a1 or the second voltage signal V _a2 falls to the zero voltage V ₀ , the voltage valley detector 131 detects the zero voltage V ₀ , so that the zero voltage V ₀ (inclusive) generates a pilot communication number T _ON , and turns on the first switching signal V _g1 , the second switching signal V _g2 , the third switching signal V _g3 or the fourth switch according to the falling edge of the guiding communication number T _ON Signal V _g4 .

Thereby, the valley voltage V _b of the resonance voltage V _r of the drain-to-source voltage V _DS1 or V _DS3 can be made lower than or equal to the zero voltage V _{0 by an appropriate design} , if the first The switching element S ₁ or the third switching element S _{3 is} turned on to achieve a zero voltage switching action.

Therefore, since the primary side of the first power conversion module 110 and the second power conversion module 111 has a zero voltage switching operation and the secondary side has a zero current switching operation, the first switching element S ₁ can be reduced. The switching loss of the second switching element S ₂ , the third switching element S ₃ and the fourth switching element S ₄ reduces the electromagnetic interference caused by the switching operation, thereby improving the first power conversion module 110 and the second power Conversion efficiency and performance of the conversion module 111.

The above-mentioned bottom voltage detection function is only one possible implementation manner, but it is not intended to limit the disclosure, and other embodiments may also achieve the above functions.

FIG. 7 is a schematic diagram showing waveforms of a switching signal generated by using a voltage valley detecting function and a cutoff signal in the control module of the present disclosure.

In the above FIG. 6 and the description thereof, the operation principle of the voltage valley detecting function has been described in detail, so the secondary side current I _S1 or the secondary side current I _S2 of the seventh figure, the first voltage signal V _a1 or The second voltage signal V _a2 , the drain-to-source voltage V _DS1 or the drain-to-source voltage V _DS3 , the conduction signal number T _{ON ,} etc., will not be repeated in detail.

As shown in FIG. 7 and FIG. 1A to FIG. 1B, when the secondary current I _S1 or the secondary current I _{S2 is} output to the AC output terminal AC _out and drops to the zero current I ₀ , the drain source voltage V _DS1 and the first voltage signal generated resonance voltage V _a1 V _r, the drain or source voltage V _DS3 signal and the second voltage V _a2 generate the resonance voltage V _r.

When the first voltage signal V _a1 or the second voltage signal V _a2 passes through the zero voltage V ₀ , the generation of the resonant voltage V _r can be known, and each resonant voltage V _r can be measured through an appropriate delay. Valley voltage V _b . At the same time, when the first voltage signal V _a1 or the second voltage signal V _a2 falls to the zero voltage V ₀ , the voltage valley detector 131 detects the zero voltage V ₀ , so that the zero voltage V ₀ (inclusive) generates a pilot communication number T _ON , and turns on the first switching signal V _g1 , the second switching signal V _g2 , the third switching signal V _g3 or the fourth switch according to the falling edge of the guiding communication number T _ON The signal V _g4 causes the primary side current I _{P1 to} store energy through the first transformer T ₁ or the primary side current I _{P2 to} pass through the second transformer T _{2 to} store energy.

Then, the pulse width modulation comparator 134 generates the cutoff signal T _OFF , and turns off the first switching signal V _g1 , the second switching signal V _g2 , and the third switching signal V according to the rising edge of the cutoff signal T _OFF . _G3 or the fourth switching signal V _g4 causes the secondary side current I _S1 or the secondary side current I _S2 to be output again to the AC output terminal AC _out to drop to the zero current I ₀ .

FIG. 8 is a schematic diagram showing a waveform of an output current of an AC output terminal, which is a first switching control strategy adopted by the DC-to-AC power conversion device of the present disclosure.

As shown in FIG. 8 and FIG. 1A to FIG. 1B, the AC waveform generator 132 generates an AC reference signal AC _ref and an AC crossover zero detection signal AC _ZCD .

When the AC reference signal AC _ref is a positive half cycle, the AC crossover zero detection signal AC _ZCD is at a high potential. The switch control strategy includes: the first switching signal V _g1 is high frequency switching, the second switching signal V _g2 is off, the third switching signal V _g3 is off, and the fourth switching signal V _g4 is conducting. Thereby, the primary side current I _P1 and the secondary side current I _S1 form a plurality of triangular waves of different sizes according to the AC reference signal AC _ref and the first switching signal V _g1 , and the contour formed by the ends of the triangular waves Similar to the sine wave, the first power conversion module 110 generates a positive half cycle of the output current I _out or the output voltage V _out .

Similarly, when the AC reference signal AC _ref is a negative half cycle, the AC cross-zero detection signal AC _ZCD is low or zero potential. The switch control strategy includes: the first switch signal V _g1 is off, the second switch signal V _g2 is on, the third switch signal V _g3 is high frequency switching, and the fourth switching signal V _g4 is off. Thereby, the primary side current I _P2 and the secondary side current I _S2 form a plurality of triangular waves of different sizes according to the AC reference signal AC _ref and the third switching signal V _g3 , and the contour formed by the ends of the triangular waves Similar to the sine wave, the second power conversion module 111 generates a negative half cycle of the output current I _out or the output voltage V _out .

FIG. 9 is a schematic diagram showing a waveform of an output current of an AC output terminal according to a second switching control strategy adopted by the DC-to-AC power conversion device of the present disclosure.

The second type is the same as the first switch control strategy and waveform diagram of Figure 8 above, so the similarities are not repeated. The main differences are as follows: as shown in Figure 9 and Figure 5, with synchronous rectification The function switching signal generator 136 is configured to synchronize the first switching signal V _g1 and the second switching signal V _{g2 to} generate a corresponding high frequency switching, or to enable the third switching signal V _g3 and the fourth The switching signal V _g4 synchronously generates a corresponding high frequency switching to achieve the effect of synchronous rectification, and reduces the body diode of the second switching element S _{2 and} the body diode of the fourth switching element S ₄ as shown in FIG. The conduction loss when the body, the first diode D ₁ or the second diode D ₂ is turned on.

FIG. 10 is a flow chart showing the steps of the DC-to-AC power conversion method of the present disclosure.

As shown in the figure, the DC-to-AC power conversion method may include the following steps:

In step S201, it is first determined whether the AC waveform generator is in the commercial parallel mode. If yes, go to step S202. If not, indicating that the AC waveform generator is in the independent mode, the process proceeds to step S204.

In step S202, the AC waveform generator is configured to generate an AC reference signal and an AC crossover zero detection signal according to the mains voltage. Then it proceeds to step S203.

In step S203, the feedback circuit generates an error signal according to the AC reference signal and the output current of the AC output terminal. Then it proceeds to step S206.

In step S204, the AC waveform generator generates the AC reference signal and the AC cross-point detection signal. Then it proceeds to step S205.

In step S205, the feedback circuit generates the error signal according to the AC reference signal and the output voltage of the AC output terminal. Then it proceeds to step S206.

In step S206, the pulse width modulation comparator generates a cutoff signal according to the error signal and the input current of the DC input terminal. Then it proceeds to step S207.

In step S207, the voltage valley detector is caused to detect or predict the valley voltage of the resonance voltage to generate a pilot number. The communication number is generated when the first voltage signal of the first auxiliary coil or the second voltage signal of the second auxiliary coil falls below the zero voltage (inclusive). Then it proceeds to step S208.

In step S208, the switching signal generator generates a first switching signal according to the AC crossover zero detection signal, the cutoff signal and the pilot signal number. No., second switching signal, third switching signal and fourth switching signal. Then, the process proceeds to step S209 or step S210.

In step S209, when the AC cross-zero detection signal is high, the first switching signal is high frequency switching, the second switching signal is off, the third switching signal is off, and the fourth switch is The signal is conductive. Then it proceeds to step S211.

In step S210, when the AC cross-zero detection signal is low, the first switching signal is turned off, the second switching signal is turned on, the third switching signal is high frequency switching, and the fourth switch is turned on. The signal is cut off. Then it proceeds to step S211.

In step S211, the first, second, third, and fourth switching signals are respectively controlled to control the first, second, third, and fourth switching elements of the first power conversion module and the second power conversion module, The first power conversion module and the second power conversion module convert the input current of the DC input terminal to an output current of the AC output terminal.

The above-described embodiments are merely illustrative of the principles, features, and functions of the present disclosure, and are not intended to limit the scope of the present disclosure. Any person skilled in the art can practice the above without departing from the spirit and scope of the disclosure. The embodiment is modified and changed. Any equivalent changes and modifications made by the disclosure of the present disclosure should still be covered by the following claims. Therefore, the scope of protection of the present disclosure should be as set forth in the scope of the patent application described later.

100‧‧‧DC to AC power conversion device

110‧‧‧First Power Conversion Module

111‧‧‧Second power conversion module

120‧‧‧ filter

121‧‧‧load

130‧‧‧Control Module

131‧‧‧Voltage Valley Detector

132‧‧‧AC waveform generator

133‧‧‧Return to the network

134‧‧‧ Pulse width modulation comparator

135‧‧‧Switch signal generator

136‧‧‧Switching signal generator with synchronous rectification

140‧‧‧ front-end DC to DC converter

AC _out ‧‧‧AC output

AC _ref ‧‧‧ AC reference signal

AC _ZCD ‧‧‧AC crossover zero detection signal

C ₁ ‧‧‧first capacitor

C ₂ ‧‧‧second capacitor

D ₁ ‧‧‧First Diode

D ₂ ‧‧‧Secondary

DC _in ‧‧‧DC input

Error‧‧‧Error signal

I _o ‧‧‧zero current

I _in ‧‧‧Input current

I _out ‧‧‧Output current

I _P1 , I _P2 ‧‧‧ primary current

I _S1 , I _S2 ‧‧‧ secondary current

N ₁ , N ₃ ‧‧‧ primary side coil

N ₂ , N ₄ ‧‧‧ secondary coil

N _a1 ‧‧‧First auxiliary coil

N _a2 ‧‧‧second auxiliary coil

S ₁ ‧‧‧first switching element

S ₂ ‧‧‧Second switching element

S ₃ ‧‧‧third switching element

S ₄ ‧‧‧fourth switching element

T ₁ ‧‧‧First Transformer

T ₂ ‧‧‧second transformer

T _OFF ‧‧‧ cut-off signal

T _ON ‧‧‧Direction number

V ₀ ‧‧‧zero voltage

V _a1 ‧‧‧First voltage signal

V _a2 ‧‧‧second voltage signal

V _b ‧‧‧ valley voltage

V _DS1 , V _DS3 ‧‧‧ bungee to source voltage

V _g1 ‧‧‧first switch signal

V _g2 ‧‧‧second switch signal

V _g3 ‧‧‧third switch signal

V _g4 ‧‧‧fourth switch signal

V _grid ‧‧‧mains voltage

V _out ‧‧‧output voltage

V _r ‧‧‧ Resonance voltage

S201~S211‧‧‧Steps

FIG. 1A is a diagram showing the DC-to-AC power conversion device of the present disclosure The circuit diagram of the first type of power conversion module.

FIG. 1B is a schematic circuit diagram of a first type of control module in the DC-to-AC power conversion device of the present disclosure.

FIG. 2A is a schematic circuit diagram of a second power conversion module in the DC-to-AC power conversion device of the present disclosure.

FIG. 2B is a schematic circuit diagram of a second control module in the DC-to-AC power conversion device of the present disclosure.

FIG. 3 is a schematic circuit diagram of a third power conversion module in the DC-to-AC power conversion device of the present disclosure.

4 is a circuit diagram showing a fourth power conversion module in the DC-to-AC power conversion device of the present disclosure.

FIG. 5 is a schematic circuit diagram of a third control module in the DC-to-AC power conversion device of the present disclosure.

FIG. 6 is a schematic diagram showing the waveforms of the secondary side current, the voltage signal of the auxiliary coil, and the conduction number in the operation principle of the voltage valley detecting function of the present disclosure.

FIG. 7 is a schematic diagram showing waveforms of a switching signal generated by using a voltage valley detecting function and a cutoff signal in the control module of the present disclosure.

FIG. 8 is a schematic diagram showing a waveform of an output current of an AC output terminal, which is a first switching control strategy adopted by the DC-to-AC power conversion device of the present disclosure.

FIG. 9 is a schematic diagram showing a waveform of an output current of an AC output terminal according to a second switching control strategy adopted by the DC-to-AC power conversion device of the present disclosure.

FIG. 10 is a flow chart showing the steps of the DC-to-AC power conversion method of the present disclosure.

S201~S211‧‧‧Steps

Claims (17)

A DC-to-AC power conversion device includes: a first power conversion module having a first transformer, a first switching element, and a second switching element, wherein the primary side coils of the first transformer are electrically connected to each other The input end and the first switching element, and the two ends of the second side coil of the first transformer are electrically connected to the second switching element and the AC output end respectively; the second power conversion module has a second transformer, a third switching element and a fourth switching element, wherein the two ends of the primary side of the second transformer are electrically connected to the DC input end and the third switching element respectively, and the two ends of the second side of the second transformer are respectively electrically connected Connecting the fourth switching element and the AC output terminal; and the control module has a voltage valley detector and an AC waveform generator, wherein the voltage valley detector detects or predicts a valley voltage of the resonance voltage to generate a pilot signal, The control module generates a first switching signal, a second switching signal, a third switching signal and a fourth switching signal according to the guiding communication number, and the first switching signal is generated by the first switching signal The second switching signal, the third switching signal and the fourth switching signal respectively control the first switching element, the second switching element, the third switching element and the fourth switching element, so that the first power conversion module and the second power The conversion module converts the input current of the DC input terminal into an output current of the AC output terminal, wherein the AC waveform generator is operated in a commercial parallel mode or an independent mode, and is configured to generate an AC reference signal according to the commercial voltage or AC crossover zero detection signal. The DC-to-AC power conversion device of claim 1, wherein the first power conversion module is configured to generate a positive half cycle of the output current, and in the positive half cycle, the first switch The signal is high frequency switching, the second switching signal is off, the third switching signal is off, and the fourth switching signal is conducting. The DC-to-AC power conversion device of claim 1, wherein the second power conversion module is configured to generate a negative half cycle of the output current, and in the negative half cycle, the first switch The signal is off, the second switching signal is on, the third switching signal is high frequency switching, and the fourth switching signal is off. The DC-to-AC power conversion device of claim 1, wherein the first switching element, the second switching element, the third switching element or the fourth switching element is a gold-oxygen half field effect transistor or an insulating gate. Bipolar transistor. The DC-to-AC power conversion device of claim 1, wherein the control module has a feedback network electrically connected to the AC waveform generator and the AC output, and according to the AC reference The signal and the output current or output voltage of the AC output generate an error signal. The DC-to-AC power conversion device of claim 5, wherein the control module has a pulse width modulation comparator electrically connected to the feedback network and the DC input terminal, and is The error signal and the input current generate a cutoff signal to turn off the first switching signal, the second switching signal, the third switching signal or the fourth switching signal. The DC-to-AC power conversion device of claim 6, wherein the voltage valley detector is electrically connected to the first auxiliary coil of the first transformer and the second auxiliary coil of the second transformer, and The first auxiliary coil and the second auxiliary coil are respectively disposed on the primary side of the first transformer and the second transformer. The DC-to-AC power conversion device of claim 7, wherein when the secondary current of the first transformer or the second transformer is output to the AC output terminal and drops to zero current, the first The first voltage signal of the auxiliary coil or the second voltage signal of the second auxiliary coil generates the resonant voltage, and the bottom voltage of the resonant voltage is lower than zero voltage. The DC-to-AC power conversion device of claim 8, wherein the voltage valley detector detects the zero voltage when the first voltage signal or the second voltage signal drops to the zero voltage And generating the communication number below the zero voltage to turn on the first switching signal, the second switching signal, the third switching signal or the fourth switching signal. The DC-to-AC power conversion device of claim 9, wherein the control module has a switching signal generator electrically connected to the AC waveform generator, the pulse width modulation comparator, and the The voltage valley detector generates the first switching signal, the second switching signal, the third switching signal and the fourth switching signal according to the AC crossover zero detection signal, the cutoff signal and the communication number. The DC-to-AC power conversion device of claim 10, wherein the switching signal generator has a synchronous rectification function for synchronizing the first switching signal and the second switching signal The high frequency switching, or the third switching signal and the fourth switching signal are synchronized to generate a corresponding high frequency switching. The DC-to-AC power conversion device of claim 1, wherein the first power conversion module has a first diode connected in parallel to the second switching element, and the second power conversion module is There is a second diode connected in parallel to the fourth switching element. The DC-to-AC power conversion device according to claim 1, further comprising a front-end DC-to-DC converter, wherein one end is electrically connected to the DC input end, and the other end is electrically connected to the first power conversion module. And the second power conversion module. A DC-to-AC power conversion method includes: generating an AC reference signal and an AC crossover zero detection signal; generating an error signal according to the AC reference signal and an output current or an output voltage of the AC output; according to the error signal and the DC input The input current of the terminal generates a cutoff signal; detecting or predicting the bottom voltage of the resonant voltage to generate a pilot signal; generating a first switching signal, a second switching signal according to the AC crossover zero detection signal, the cutoff signal and the pilot number, The third switching signal and the fourth switching signal; and the first switching signal, the second switching signal, the third switching signal and the fourth switching signal respectively controlling the first power conversion module and the second power conversion module Switching element, second switching element, third The switching element and the fourth switching element enable the first power conversion module and the second power conversion module to convert an input current of the DC input terminal to an output current of the AC output terminal. The DC-to-AC power conversion method of claim 14, wherein the method further comprises: determining whether the AC waveform generator is in the mains parallel mode; and if so, causing the AC waveform generator to generate the AC reference signal according to the mains voltage and The AC crosses the zero point detection signal. If not, the AC waveform generator generates the AC reference signal and the AC crossover zero detection signal by itself. The DC-to-AC power conversion method of claim 14, wherein the first switching signal is a high frequency switching and the second switching signal is when the AC zero crossing detection signal is high. For the cutoff, the third switch signal is off, the fourth switch signal is turned on; and when the AC crossover zero detection signal is low, the first switch signal is turned off, and the second switch signal is turned on. The third switching signal is a high frequency switching, and the fourth switching signal is a cutoff. The DC-to-AC power conversion method according to claim 14, wherein the communication number is generated when the first voltage signal of the first auxiliary coil or the second voltage signal of the second auxiliary coil falls below zero voltage .